Color photography



V. v WEIL COLOR PHOTOGRAPHY Filed- 001;. a, 1925,

6 color screen.

panehramafic emulsion.

support I 6- very narrow spaces f0 permi/ chemioa/s f0 penal'rafe f0 fhe panchromafic emulsion.

// very fine passages f0 permil' chemicals f0 penefrafe f0 fhe calqr screen formed of siurch qrairis J; pdnch omafic or fhe like. emulsion.

. 5 anchroma I'C I Support liven/151'.-

llmtov WE/L I Jtt'orneys.

' as of developing Patented Nov. 30, 1926.

VALENTIN warn, or nnncnni ennraenr.

tsoazsz rice.

' 0010B PHGTOGBAPHY.

Application file d October 8, 1925Q8erial Ito. 83,299, and in Germany hugust 28, 1923.-

The invention relates to the production or cinematographic films or the like, in natural colors by the employment of light filters or color screens, and an object of the invention a is to superimpose' the transparent composition which constitutes the light filter di rectly upon the sensitized layer of the film in such a manner as not to afi'ect the action of the developing and fixing baths.

1a A further object of the invention is to provide for transferring the composition to the film by mechanical printing means.

. The production of colored cinematographic films, photographic transparencies 1e and paper prints by photographic means is quite possible theoretically with the assistance of a=color screen or lightfilter. The known methods of producing such color screens are however troublesome and are not 7 530 sufficiently reliable to be applied in practice precautions either to films or to paper prints.

without further The colored screen members have not been sufficiently resistant to withstand the action and fixing. baths. Hence hitherto it has been necessary to introduce I the color screen only beneath the photographic layer and to protect it by means of a coating of lacquer.

It has been universally assumed hitherto that extremely light filtering particles were necessary for the making of successful screens for taking photographs. Experiments have shown however that it is possible to produce perfeet color pictures by the use of a color screen composed of color elements or particles which are verymuch larger than the granules which have been hitherto used in such screens. k

Knowledge of the abovefact has suggested that it should be possibleto make such a color screen in a very simple and cheap manher by a suitable mechanical printing proc ess and it-has been proved that filter elements could be reproduced free from defects printing methods.- By such methods no difficulties were met with provided the printed color screen could be made in such a way that in the printing of the color screen the points of color came to lie side by side so that a completely closed-color screen was produced although this result need not ac: tually be attained in practice because the color elements are likely to overlap and yet this does not produce any serious optical small color screen particles or defect. It the surface of the film is not completely covered with color elements any optical defect can be ignored as practically not noticeable with the size of filter elements used for the present purpose and it produces noticeable efi'ects in the diffraction of light only if the size of the areas is extremely small.

According tothe present invention the color areas are produced by direct mechanical printing methods using any suitable printlng process, even'a stereotype rocess using appropriate printing. colors aving the right optical efi'ects.

The advantage of this process consists in the cheap production of color screens of any desired size, and in the possibility of making such screens with color points in them of an desired size, as also in tha fact that the co ors can not be attacked by the developing v (Gao m zr and the like are deposited as color lakes on a suitable base such for ium hydroxide. This thoroughly ground orrubbed together with linseed oil varnish 'and suitable additibns fish for example as copal, dammar and the 1 e, having excellent light-filtering qualities.

While making use of this cial light-separating properties are to be.

given to the,varnish.- The light-filter coloring matters produced for prmting'as above are therefore much-better in regardtov their then give a crystal clear printing color case by further grinding or if the production of the example as alumin colormg matter when For the purpose in view also fat soluble transparency and permanence of color than v as color filter it is necessary'to employ filter the light-filter granules which have been used hitherto. Thorough researches have proved that from the tical pomt of v1ew color screens of high e ciency can be produced in this way.

The present invention is illustrated in the accompanying drawings, in which,

Fig. 1 is a erspective view of a film embodying one orm of the invention;

, to netrate to the sensitized layer 5.

Fig. 2 is a similar View of a modification.

In Fig. 1, 4 represents the support, of eelluloid or other material, carrying a panchromatic emulsion layer 5. Upon layer 5 is imposed, by suitable printing means, a color screen 6, consisting of small areas or points of difierently colored elements 7, separated by very narrow spaces 8, which permit the developing and fixing'chemicals A parencies it sufiices to use light-filter elements of a size such as is used in the screens of modern printing blocks (see Fig. 1).

i have been'practiea lly this purpose colore 40 For projection pictures however such as cinematograph films and the like which are- 'required to be capable of very great enlargement without displaying the pattern of the elements which are smaller than any which possible hitherto. For pigments such as the Veryfinest starch grains or the like, or even the larger colloids may be mixed direct with the varnish and any other necessar additions, and worked u into .a printab e filter to form a color screen (see 1 For example'two or more colored pigment color, and t is latter can be'applied to the film by any suitableprinting process ments may be introduced directly into jthe color produced as above described with aluminium hydroxideso that the color of a pigment is replaced by a light-filter coloring matter. The direct coloring ofthe adjacent filter particles. one by another cannot occur because the colorin matter used is in the most finely divided orm.

In order to render it possible to transfercopies of a color filter plate upon; another co or filter plate, the color areas of the color screen on which the co y is to be: made,

; should be larger than t ose of the screen withwhich the photograph was taken. This requirement can easily be complied with by the printing process and itis of advantage in; that it permits of the production of color screen elements of' successively increasing.

size. The process offers the possibility at once of making the various color elements of variable area in lan while they are of the same height so tiat their area may be increased for example. This is of importance because the color screen elements should be able to expand in area but should not be able to increase in height in order that'they may not have an unfavorable action as regards transparency to light. In order to render it possible to apply the color screen upon the photographic layer and yet to permit the plate or film to be developed although the color screen itself is not permeable by the developing and fixing baths, extremely small spaces as already mentioned which are not directly visible to the eye are left in the screen. The developer passing through these s aces comes first into contact 'with the sensitlzed layer which consists of an absorbent mass such as gelatine or the like, and it is then di?ersed by lateral spreading into the areas eneath the actual color screen elements Experiments have shownthat these small gaps or spaces between the color screen elements produce no optical-defe'cts. They may hbyveve'r be filled up with soot or lamp black for example without interfering with th permeability of the layer to the developing and fixing solutions.

A "plate or film produced as above described only requires about a quarter of the time of exposure that required for the well known auto chrome plates having a color screen beneath the) hotographic layer, so that by the use of this invention it is possible to take snap-shots by the use of a rapid objective lens with very short exposures.

Having thus described my invention what .I claim as new and desire to secure by Let ters Patentis 1. Process 'for. the production of a hotographic sensitized surface for color p iotograp y consisting in "impressing upon the light sensitivelayer a multi-color screen by means of mechanical printing with light transmitting coloring matter, the color elements'of the. screen consisting of points of color separated by very small spaces through which the solutions used in preparing the photogra hic prints can penetrate down to the absor nt sensitized layer.-

2. Process for theproduction of a photographic sensitized surface for color hotography .consisting'in making a mec anical printing composltion from very fine colored particles and printing mechanically a screen with the said-composition on the photographic sensitized surface.

3. lfi'ocess for the production of a hotogra c sensitized material for color p otograp y consi'stingnn a plying a light sensitive emulsion to'a WfiItG background, and

impressing u on said emulsion by mechani- "film for color photography, comprising superimposing a light filter upon the sensitized surface of the film by mechanical printing means, said light filter being made up of points of colored matter separated from each other by spaces through which chemicals may penetrate to the sensitized surface. Y

trate to said layer.

5. film for color photography, compris ing a support, a panchromatic emulsionlayer on said support, and a color screen on said panchromatic layer, said color screen consisting of color elements separated from 'each other by narrow spaces extending both longitudinally and transversely of the film and adapted to permit chemicals to pene- In wit-nesswhereofl afiix my signature.

VALENTIN WEIL. 

